Sand milling machine



Nov. 19,1940, WALTH ER 2,222,054

SAND MILLING MACHINE Filed Aug. 4, 1939 INVENTOR G FOR E WALTHER ATTORNEYS Patented Nov. 19, 1940 PATENT OFFICE 1 sum) MILLING MACHINE George, Walther, Dayton, Ohio, assignor to The Dayton Steel Foundry Company, Dayton, Ohio,

a corporation of Ohio Application August 4, 1939, Serial No. 288,459

4 Claims.

This invention relates to apparatus for originally conditioning as well as reclaiming and reconditioning molding or foundry sand employed for molds and cores of various types for the casting of metal in foundries. Sand for this process is required to be specially conditioned and mixed with core .oil, bonding material and other ingredients in accordance with certain well-known formulae, depending upon the nature of the use for which the sand is to be prepared.

Various types of apparatus comprising instrumentalities for working or mulling the sand to properly condition and entirely mix the same with the other ingredients desired to be incorporated therewith have been designed, and this invention has particular reference to the type of such machines comprising one or more heavy rollers adapted to move in a circular orbit over a platform upon which sand to be mulled is supported. g

The present types of such machines usually comprise a horizontal platform for supporting the sand to be conditioned and partially supporting one or more very heavy rollers journalled upon horizontal axes extending radially from a vertical shaft rotated from a suitable source of power. Rotation of the vertical shaft causes the rollers to move in a circular orbit about the supporting platform during which process the sand is engaged between the peripheries of the rollers and the supporting platform to effect a mulling action upon the sand whereby the sand is compressed by the gravitational force of the rollers and mixed by reason of the movement of said rollers therethrough. The compressing phase of the mulling action is secured primarily as a result of the weight of the rollers which are necessarily of very heavy and cumbersome construction for the purpose.

The construction of machines of the type just described is such that, in the operation thereof, movement of the massive rollers required creates a tremendous centrifugal thrust which places a very heavy burden upon the bearing structure by which said rollers are connected to the vertical motive shaft, as well as upon the fastening means by which the rollers are secured to shafts upon which the same are journaled. Consequently, the speed at which such machines may be operated is necessarily comparatively slow if the con struction of their parts is not to be prohibitively heavy, cumbersome and costly.

The construction of such machines in accord- Vere physical limitations on the capacity thereof or the amount of sand which may be properly conditioned thereby within a given period. This is an important factor in foundry costs and practice.

It is a primary object of the present invention to provide a construction of sand milling machine in which the speed at which the same may be operated, and consequently the productive capacity and general efficiency thereof, is substantially increased without increasing the weight, or strength of construction of the parts and without materially increasing their cost.

Another object of the invention is to provide a construction of sand milling'machine of the type described in which the centrifugal thrust created in the operation thereof is materially reduced and consequently the strain upon the bearing structure and means for fastening the rollers to the shafts upon which they are journaled is reduced to a minimum.

A further object of the invention is to provide -a construction .of sand milling machine in Which the weight of the rollers may be materially reduced, if desired, without sacrificing the advanrollers over the sand to be conditioned and means for connecting said rollers to the vertical motive shaft at an angle thereto corresponding tothe angle of the inclined track in such a manner that said rollers are yieldable toward and away from said inclined track supporting the sand to be conditioned.

The details of my invention will now be described in conjunction with the accompanying drawing in which Figure 1 is a top plan view of a device embodying my invention.

Figure 2 is a sectional view taken on the line 22 of Figure 1.

Figure 3 is a View taken on the line 33 of Figure 1.

Figure 4 is a viewtaken at right angles to the view of Figure 3.

Now referring to the drawing, the numeral l indicates a hopper or container, having an in- .clined portion l-a and a horizontal bottom portion lb. The hopper or container l is adapted to contain foundry sand to be conditioned, same being loaded into the hopper through the open top portion and being discharged through the orifice 2 in the inclined portion |a, which orifice is normally closed by a plate 3, pivoted as at 4 to the under side of the inclined portion |-a of said hopper.

The hopper I is supported by means of frame members 5 upon the foundry floor or other supporting surface. A driving shaft 6 extends through a suitable bearing opening 5-a in one of the frame members 5, and through a suitable bearing member I! secured to the bottom |b of the hopper. To the outer end of said shaft 3 is secured a pulley 8 connected to a suitable source of power. Secured to the inner end of said shaft 6 is a beveled pinion 9 meshing with a beveled gear |lJ keyed to the lower end of a shaft H and locked fast to said shaft by means of a suitable nut |2 cooperating with the threaded lower end of said shaft A hub member 13 secured to the shaft II by means of a pin I4 is rotatably supported upon a fixed bearin'g member |5 by means of roller bearing l6, intermediate said hub member and said fixed bearing I5. The fixed bearing member I5 is secured to the bottom portion |b of the hopper I by means of screws or other suitable fastening means. The roller bearing I6 has bearing races l8 and I9 cooperating with suitable recesses provided respectively in the fixed bearing member l5 and the member l3.

The member I3 is provided With an annular flange |3a from which depend the inclined bearing portions 23 and 2|.

Crank members 22 and 23 are pivotally coninected with the bearing portions 20 and 2| respectively by means of pivot pins 24 and 25 respectively, the inner ends of which are journaled in said bearing portions 28 and 2| respectively. Secured to the free ends of the crank members 22 and 23 are stub shafts 26 and 21 upon which are respectively journaled the milling rollers 28 and 29. Hub member 13 with its portions 20 and 2| provides a carriage for the rollers 28 and 29.

Formed integral with and depending vertically from the annular flange |3--a. are the flanged portions 38 and 3| disposed at diametrically opposite edges of the annular flange |3a. To the depending flanged portions 38 and 3| are respectively secured the brackets 32 and 33 by means of screws 34. An upper plow member 35 and a lower plow member 35 are carried by the bracket 32, and similarly an upper plow member 31 and a lower plow member 38 are carried by the bracket 33. The upper and lower plow members are oppositely curved for a purpose hereinafter mentioned.

In operation, foundry sand to be conditioned will be loaded into the hopper I through the open top portion thereof and the pulley 8 rotated in the direction of the arrow to cause rotation of the shaft II and consequently of the member I3 in a counter-clockwise direction, having reference to Figure 1. The milling rollers 28 and 29 will thus travel in a circular orbit about the central axis represented by the shaft upon the inclined track provided by the inclined portion |a of the hopper In the course of their travel, the said rollers 28 and 29 are yieldable vertically respecting the inclined portion |a of the hopper by reason of the pivotal movement of the cranks 22 and 23 about their respective pivots 24 and 25 to accommodate between the peripheries of said rollers and said hopper the sand contained in the latter.

Rotation of the member I3 causing movement of the rollers 28 and 29 in their circular orbit about the hopper I also causes the plow members 35, 35, 31 and 38 to be moved through the sand therein contained to agitate the same and plow it into the path of movement of said rollers. For this purpose, each of the upper plow members 35 and 31 extends outwardly from the central axis farther than the lower plow members and is curved away from the respective roller to which it is nearest. The upper plow members 35 and 31 tend to move the sand away from the sides of the hopper, inwardly toward the center thereof and into the path of movement of the rollers 28 and 29. Each of the lower plow members 38 and 38, on the other hand, is curved toward the respective roller member to which it is nearest, and consequently said lower plow members tend to move the sand away from the center of the hopper and into the path of movement of the rollers 28 and 29.

In previous constructions of sand milling machines involving a horizontal platform for supporting sand to be conditioned and milling rollers mounted upon horizontal axes for movement in a circular orbit about said horizontal platform, no provision is made for counteracting the centrifugal force resulting from movement of the milling rollers so mounted in their circular orbit.

Consequently, in such constructions a horizontal thrust of considerable proportions is sustained by the motive shaft and the bearing members corresponding to the members l5 and I8 of the present construction as well as upon the means by which said rollers are fastened.

In the construction of my invention, on the other hand, by reason of the fact that the axes of the rollers 28 and 29 are inclined to the horizontal so as to travel upon the inclined track provided by the portion |a of the hopper the centrifugal force resulting from the movement of said rollers in their circular orbit about the shaft II is counteracted by engagement of the inclined portion l-a with the peripheries of said rollers through the medium of the intervening foundry sand in the hopper I. The centrifugal'thrust sustained by the shaft II and bearing members l5 and I6 during operation of the device of my invention is therefore greatly reduced by the provision of inclined axes for the rollers and the design of the hopper providing an inclined track portion for travel of said rollers.

Consequently a milling machine constructed according to my invention is capable of being operated satisfactorily at much higher speeds than are practicable in the employment of machines or comparable size, constructed in accordance with previous designs. For example, a milling machine of a certain size constructed in accordance with the previous design, having its milling rollers mounted upon horizontal axes to travel about a horizontal platform, is capable of being operated at a speed of twenty to thirty revolutions of its vertical motor shaft per minute. A machine of comparable size and proportioning of parts constructed in accordance with my invention, on the other hand, may be operated at speeds of fitty to sixty revolutions of the shaft per minute without placing any greater strain upon the parts.

In the construction of sand milling machines in accordance with my invention, moreover, the weight of the rollers 28 and 29 may be materially reduced from thatwhich was required. to'ob tain proper conditioning action in'previous con structions of the type mentioned by vreason'of the fact that in the construction of my invention the centrifugal force resulting from the :movement of the rollers about the inclined portion |a of the hopper l augments the gravitational force exerted by said rollers upon:the sand in the path of movement thereof insaid hopper. In other words, the gravitational force of the rollers 28 and 29, represented by the weight of said rollers, is exerted against the sand-between the peripheries of said rollers and the inclined portion I-a of said hopper,-and likewise the centrifugal force resulting from the movement of said rollers is exerted upon the sand between the peripheries of said rollers and the inclined portion la in a direction at a right angle to said inclined portion of th hopper. Thus, when the carriage is rotated, the force exerted by the rollers 28 and 29 upon the sand in their'path of movement is a combination of-the gravitational forces of said rollers and the centrifugal force resulting from their movement. This combination of forces, rather than the Weightof the rollers alone, is relied on to secure proper'conditioning action in my construction. The weight of the rollers in my construction may be considerably reduced from that which was required in previous constructions to obtain the same effect.

The shaping of the plow members 35, 36, 3'! and 38 as herein disclosed is important in scour ing an agitation of the sand in the hopper I that enables not only thorough and rapid mixing, but more rapid movement of the sand into the path of the rollers, thereby reducing the number of revolutions of the carriage required for conditioning of the sand by the rollers. For the same reason the time required for discharge of the sand through the opening 2 upon completion of the conditioning operation is shortened, effecting economy in time required for operation.

It will be seen, therefore, that in the construction of sand milling machines herein described, objectionable horizontal thrust is greatly rereduced, enabling economies in construction to be effected resulting from reduced requirements for weight and strength of parts; the centrifugal force, which in previous constructions was responsible for this objectionable thrust, in my construction is utilized to advantage in securing proper milling action, thereby enabling employment of rollers of reduced weight and effecting further economy of construction; and, of prime importance, my construction enables operation of the mill at higher speed and the agitating action is such as to cut down the time required for conditioning as well as discharge, resulting in substantial increase not only in productive capacity but also in efilciency of operation.

The positioning of the discharge opening 2 at the lower end of the inclined surface la is advantageous because it permits the sand to be more quickly discharged from the hopper, by reason of the fact that sand resting on the inclined surface tends to move toward said opening by gravity when the plate 3 is moved to non-closing position.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a device of the class described, in combination, a rotatable carriage, a hopper having a supporting surface extending circumferentially about the axis of said carriage for supporting sand to be conditioned, a rotatable member secured to said carriage and supported by said surface for movement thereover, a plow member secured to said carriage and extending in a reverse curve to a point outwardlyof the path of movementuof said rotatable member, the inner portion of said plow member having a curvature toward said rotatable member and the outer portion of said plow member having a curvature away from said rotatable member, and means for rotating said carriage to cause movement of said rotatable member in a circular orbit about said axis and to cause movement of said plow member through sand supported by said surface, the.

outer portion of said plow member moving sand engaged thereby and lying outwardly of said rotatable member in a direction toward said carriage andinto' the path of said rotatable member, and the inner portion of said plow member moving sand engaged thereby and lying inwardly of said rotatable member in a direction away from said carriage and into the path of said rotatable member.

2. In a device of the class described, in combination, a rotatable carriage, a hopper having a supporting surface extending circumferentially about the axis of said carriage for supporting sandto be conditioned, a rotatable member secured to said carriage and supported by said surface for movement thereover, an upper plow member secured to said carriage and extending in a reverse curve to a point outwardly of the path of movement of said rotatable member, the innerportion of said plow member having a curvature toward said rotatable member and the outer portion of said plow member having a curvature away from said rotatable member, a lower plow member secured to said carriage and extending outwardly therefrom to a point inwardly of the path of movement of said rotatable member and curved in a direction toward said rotatable member, and means for rotating said carriage to cause movement of said rotatable member in a circular orbit about said axis and to cause movement of said plow members through sand supported by said surface, the upper plow member engaging the upper portion of the body of sand, the outer portion of said upper plow member moving sand engaged thereby and lying outwardly of said rotatable member in a direction toward said carriage and into the path of said rotatable member, and the inner portion of said upper plow member moving sand engaged thereby and lying inwardly of said rotatable member in a direction away from said carriage and into the path of said rotatable member, and said lower plow member engaging the lower portion of the body of sand and moving sand so engaged and lying inwardly of said rotatable member in a direction away from said carriage into the path of movement of said rotatable member.

3. In a device of the class described, in combination, a rotatable carriage, a hopper having a supporting surface extending circumferentially about the axis of said carriage for supporting sand to be conditioned, a rotatable member disposed on either side of said carriage and secured thereto, a set of upper and lower plow members secured to said carriage on either side thereof and extending therefrom adjacent to, and in a general direction approximating an acute angle to the axis of one of said rotatable members, the upper plow member extending from said carriage in a reverse curve to a point outwardly of the path of movement of its adjacent rotatable member, the inner portion of said upper plow member having a curvature toward its adjacent rotatable member and the outer portion of said upper plow member having a curvature away from its adjacent rotatable member, the lower plow member extending from said carriage to a point inwardly of the path of movement of its adjacent irotatable member and curved in a direction toward its adjacent rotatable member, and means for rotating said carriage to cause movement of said rotatable members in a circular orbit about the axis of said carriage and to cause movement of said plow members through sand supported by said surface, the upper plow member engaging the upper portion of the body of sand, the outer portion of said upper plow member moving sand engaged thereby and lying outwardly of its adjacent rotatable member in a direction toward said carriage and into the path of its said adjacent rotatable member, and the inner portion of said upper plow member moving sand engaged thereby and lying outwardly of its said adjacent rotatable member in a direction away from said carriage and into the path of movement of its said adjacent rotatable memher, and said lower plow member engaging the lower portion of the body of sand and moving sand so engaged and lying inwardly of its adjacent rotatable member away from said carriage into the path of movement of its said adjacent rotatable member.

4. In a device of the class described, in combination, a rotatable carriage, a hopper having a supporting surface extending circumferentially about the axis of said carriage for supporting sand to be conditioned, and comprising an outer inclined portion and anvinner horizontal portion, said surface having a discharge opening at the lower extremity of said incline, a rotatable member secured to said carriage and supported by said surface for movement thereover, a plow member secured to said carriage and extending in a reverse curve over the inclined portion of said surface to a point outwardly of the path of movement of said rotatable member, the inner portion of said plow member having a curvature toward said rotatable member over the inner horizontal portion of said surface and the outer portion of said plow member having a curvature away from said rotatable member over the inclined portion of said surface, a second plow member secured to said carriage and extending therefrom to a point inwardly of said opening and inwardly of the path of movement of the rotatable member and curved in a direction toward said rotatable member, and means for rotating said carriage to cause movement of said rotatable member in a circular orbit about said axis and to cause movement of said plow members through sand supported by said surface, the outer portion of said first plow member moving sand engaged thereby and lying outwardly of said rotatable member in a direction toward said opening and downwardly of said incline toward said opening and said second plow member and the inner portion of said first plow member moving sand engaged thereby and lying inwardly of said rotatable member in a direction away from said carriage along the horizontal portion of said surface toward said opening and into the path of said rotatable member.

GEORGE WALTHER. 

